Antiferromagnetic insulating state in layered nickelates at half filling

Abstract

We provide a set of computational experiments based on ab initio calculations to elucidate whether a cuprate-like antiferromagnetic insulating state can be present in the phase diagram of the low-valence layered nickelate family (Rn+1NinO2n+2, R= rare-earth, n= 1 - ∞) in proximity to half-filling. It is well established that at d9 filling the infinite-layer (n= ∞) nickelate is metallic, in contrast to cuprates wherein an antiferromagnetic insulator is expected. We show that for the Ruddlesden-Popper (RP) reduced phases of the series (finite n) an antiferromagnetic insulating ground state can naturally be obtained instead at d9 filling, due to the spacer RO2 fluorite slabs present in their structure that block the c-axis dispersion. In the n= ∞ nickelate, the same type of solution can be derived if the off-plane R-Ni coupling is suppressed. We show how this can be achieved if a structural element that cuts off the c-axis dispersion is introduced (i.e. vacuum in a monolayer of RNiO2, or a blocking layer in multilayers formed by (RNiO2)1/(RNaO2)1).